In a multi-operating system (OS) having a plurality of OSs in a single system, each OS can execute respective processes on hardware common to the system, such as a central processing unit (CPU) and a memory, successively switched in time sequences.
Scheduling of processes (tasks) of a plurality of OSs is executed by a partition management software program, for example. If an OS(α) and an OS(β) coexist in a single system with the process of OS(α) being a partition A and the process of OS(β) being a partition B, the partition management software program determines the scheduling of the partition A and the partition B, and executes the process of the OSs with the hardware resources allocated based on the determined scheduling.
Patent Document 1 discloses a task management technique of a multi-OS system. According to the disclosure, tasks to be executed by a plurality of OSs are scheduled with a priority placed on a process having urgency.
An entity processing data is set up as a partition. More specifically, a logical partition is set up as an entity that shares resources in a system. A variety of resources such as use time of the physical processor, virtual address space, and memory space are allocated to the logical partition. The process is then performed using the allocated resources. A logical processor corresponding to any physical processor is set up in the logical partition, and data processing is performed based on the logical processor. The logical processor does not always correspond to the physical processor on a one-to-one correspondence. For example, a single logical processor can correspond to a plurality of physical processors, and a plurality of logical processors can correspond to a single physical processor.
If a plurality of processes are performed in parallel using the logical processor, the physical processor is used by scheduling the plurality of logical processors. More specifically, the plurality of logical processors uses the physical processor in a time-sharing manner.
In the multi-OS, hardware resources such as physically available processors are limited. A physical processor, currently used by one OS, cannot be used by another OS. A duration throughout which the processor cannot be used by another OS is referred to as an interrupt mask period. As the interrupt mask period is prolonged, the efficiency of the entire system is decreased.    [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2003-345612